1. Field
This disclosure relates generally to tracking interactions of mobile users.
2. Background
As the utility and affordability of mobile terminals (smartphones, tablet computers, etc.) improve, an increasing number of users carry one or more mobile terminals for most of the day. Many mobile terminals have embedded global position system (GPS) devices that facilitate the determining of the mobile terminal's, and therefore, the user's location. Wireless network operators can collect user movement information including locations by using such embedded GPS devices as the users move from one wireless network coverage area to another.
However, GPS may not provide an adequate level of accuracy in some applications. Moreover, GPS may either be unavailable or unreliable in indoor and other environments in which a clear view of the sky is obstructed to some degree. Some systems utilize WiFi networks to achieve a higher degree of accuracy than what is afforded by GPS. Mobile terminals are, in general, surrounded by WiFi Access Points (APs). The strength of the signal received from an AP by a mobile terminal (MT) depends on several factors such as distance and the presence of obstacles. For any given location, a MT may receive signals from several APs with specific signal strengths. Therefore, it is possible to define a “WiFi fingerprint” as a set of signal strength measurements associated with APs. The APs are also characterized by their respective MAC addresses.